In recent years, various types of flat panel displays have been developed. With their ability to achieve reduced power consumption, thinner profiles, and higher picture quality, organic Electro luminescence (EL) display devices in particular are attracting attention as excellent flat panel displays.
When manufacturing an organic EL display device, a method is typically used in which a constant gap between a vapor deposition mask and an active matrix substrate is ensured by providing an edge cover (also called a “bank material” or a “partition material”) having a constant height on the active matrix substrate, and a vapor deposition film is then formed using the vapor deposition mask.
PTL 1 and 2 disclose organic EL display devices configured including such an edge cover on the active matrix substrate.
FIG. 14A is a diagram illustrating the overall configuration of a known organic EL display device 101 including an edge cover 112 having openings 112a, and FIG. 14B is a diagram illustrating a problem with the known organic EL display device 101 including the edge cover 112.
As illustrated in FIG. 14A, the organic EL display device 101 includes a substrate 102, active elements 103 (e.g. TFT elements) formed on one face of the substrate 102, an insulating layer 104 covering the active elements 103, first electrodes 105 (e.g. ITO) electrically connected to the active elements 103 with contact holes formed in the insulating layer 104 therebetween, and the edge cover 112 formed covering the insulating layer 104 exposed between end portions of adjacent first electrodes 105 and the end portions of the first electrodes 105.
In the organic EL display device 101, a hole injection layer (HIL layer) 106 and a hole transport layer (HTL layer) 107 are furthermore formed above the substrate 102 covering the first electrodes 105 and the edge cover 112.
A red light emitting layer (EML layer) 108R, a green light emitting layer (EML layer) 108G, and a blue light emitting layer (EML layer; not illustrated) are formed on the hole injection layer 106 and the hole transport layer 107 above the regions where the first electrodes 105 are formed.
An electron transport layer (ETL layer) 109 and an electron injection layer (EIL layer) 110 are formed above the substrate 102 covering the hole transport layer 107, the red light emitting layer 108R, the green light emitting layer 108G, and the blue light emitting layer (not illustrated). A second electrode 111 (e.g. a metal layer) is formed above the substrate 102 covering the electron injection layer 110.
FIG. 15 is a diagram illustrating a process of manufacturing the known organic EL display device 101 illustrated in FIG. 14A.
In the organic EL display device 101, the hole injection layer 106 is formed above the substrate 102, covering the first electrodes 105 and the edge cover 112, using an open mask (S101).
The hole transport layer 107 is then formed above the substrate 102, covering the hole injection layer 106, using an open mask (S102).
Then, the red light emitting layer 108R, the green light emitting layer 108G, and the blue light emitting layer (not illustrated) are formed on the hole injection layer 106 and the hole transport layer 107 above the regions where the first electrodes 105 are formed, using three coloring masks (S103).
The electron transport layer 109 is then formed above the substrate 102, covering the hole transport layer 107, the red light emitting layer 108R, the green light emitting layer 108G, and the blue light emitting layer (not illustrated), using an open mask (S104).
After this, the electron injection layer 110 is formed above the substrate 102, covering the electron transport layer 109, using an open mask (S105).
Finally, the second electrode 111 is formed above the substrate 102, covering the electron injection layer 110, using an open mask (S106).
The organic EL display device 101 including red light-emitting organic EL elements, green light-emitting organic EL elements, and blue light-emitting organic EL elements can be realized through this procedure.
In recent years, highly electrically conductive P-doped hole injection layers, highly electrically conductive P-doped high-polymer hole injection layers, and the like are more commonly being used as the hole injection layer 106. Additionally, there is a trend toward using a shape having a sharp taper angle for the edge cover 112 in order to increase the resolution.